The present invention relates to structure and process for producing optical components and optical structures that are particularly useful in a lithographic imaging optical system.
In imaging optical systems, e.g. microlithography imaging optical systems for imaging (“printing”) a wafer, there is a continuing need for optical structures that can image (“print”) small features on a sample such as a wafer that is imaged by the microlithography imaging system.
In addition, in the applicants' experience, there is also a need for optical structures that can image relatively small wavelengths (e.g. in the extreme ultra violet range), at relatively high numerical aperture (NA) with a large field of view and with small residual aberrations. Such optical structure is particularly desirable in a microlithography imaging optical system because it enables smaller features to be printed on a wafer with very small distortion.
Moreover, in the applicants' experience, if the amount of asymmetry of such optical structure is relatively small, the optical structure is also desirable because current manufacturing techniques can be used in the manufacture of the optical structure components.